Sodium Excess Ta‐Modified (K _0.5 Na _0.5 )NbO ₃ Ceramics Prepared by Reactive Template Grain Growth Method

Lead‐free sodium excess Ta‐modified (K _0.470 Na _0.545 )(Nb _0.55 Ta _0.45 )O ₃ ( KNNT ) ceramics were synthesized by a conventional and reactive templated grain growth methods, and their degree of grain orientation, microstructure, dielectric, ferroelectric, and field‐induced strain properties were systematically investigated. A high degree of grain orientation (Lotgering factor F = 80%) was obtained in textured KNNT ceramics. Results showed that textured KNNT ceramics exhibit high grain orientation, dielectric constant, and field‐induced strain as compared to nontextured samples of the same composition. Room temperature unipolar field‐induced strain of K _0.5 Na _0.5 NbO ₃ ( KNN ) ceramics was enhanced from 0.080% for nontextured sample to 0.115% for textured sample, and their corresponding dynamic piezoelectric coefficients ( ) were improved from 320 pm/V to 460 pm/V, respectively.